For every four days or part thereof of travel across the Wasteland, one tests on:
(Luck + (Survival : 25)) using a D10.
If the test succeeds, there is a positive random encounter. If it fails, a negative one.
Caravans test on a fixed value of 5.
Groups of several characters use the best value within their group.
To determine what kind of positive or negative encounter happens, one can roll a D20 and go by the list below.
Positive encounters
1 - 10: No encounters
11 - 12: A small trading group that sells medical supplies and food.
13 – 14: A small trading group selling weapons and armor.
15 – 16: A small trading group, selling luxury items, exotics and pre war devices.
17: A bard or several bards..
18: a friendly, but heavily armed group of mercenaries/bounty hunters.
19: A herd of brahmin.
20: A lone wanderer/ a hermit / a tourist.
Negative encounters
1: Deathclaws
2: Rats
3: Wolves or wild dogs
4: Radscorpions
5: Giant mantises
6 – 9: Feral ghouls
10 – 14: A band of Raiders or Slavers (not in NCR territory, here one would meet a patrolling group of Rangers).
17: Spore plants
18: Sand storm
19: Very strong rain
20: incredible heat